path: root/crypto/skcipher.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Symmetric key cipher operations.
 *
 * Generic encrypt/decrypt wrapper for ciphers, handles operations across
 * multiple page boundaries by using temporary blocks.  In user context,
 * the kernel is given a chance to schedule us once per page.
 *
 * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
 */

#include <crypto/internal/aead.h>
#include <crypto/internal/cipher.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/bug.h>
#include <linux/cryptouser.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <net/netlink.h>
#include "skcipher.h"

#define CRYPTO_ALG_TYPE_SKCIPHER_MASK	0x0000000e

enum {
	SKCIPHER_WALK_PHYS = 1 << 0,
	SKCIPHER_WALK_SLOW = 1 << 1,
	SKCIPHER_WALK_COPY = 1 << 2,
	SKCIPHER_WALK_DIFF = 1 << 3,
	SKCIPHER_WALK_SLEEP = 1 << 4,
};

struct skcipher_walk_buffer {
	struct list_head entry;
	struct scatter_walk dst;
	unsigned int len;
	u8 *data;
	u8 buffer[];
};

static const struct crypto_type crypto_skcipher_type;

static int skcipher_walk_next(struct skcipher_walk *walk);

static inline void skcipher_map_src(struct skcipher_walk *walk)
{
	walk->src.virt.addr = scatterwalk_map(&walk->in);
}

static inline void skcipher_map_dst(struct skcipher_walk *walk)
{
	walk->dst.virt.addr = scatterwalk_map(&walk->out);
}

static inline void skcipher_unmap_src(struct skcipher_walk *walk)
{
	scatterwalk_unmap(walk->src.virt.addr);
}

static inline void skcipher_unmap_dst(struct skcipher_walk *walk)
{
	scatterwalk_unmap(walk->dst.virt.addr);
}

static inline gfp_t skcipher_walk_gfp(struct skcipher_walk *walk)
{
	return walk->flags & SKCIPHER_WALK_SLEEP ? GFP_KERNEL : GFP_ATOMIC;
}

/* Get a spot of the specified length that does not straddle a page.
 * The caller needs to ensure that there is enough space for this operation.
 */
static inline u8 *skcipher_get_spot(u8 *start, unsigned int len)
{
	u8 *end_page = (u8 *)(((unsigned long)(start + len - 1)) & PAGE_MASK);

	return max(start, end_page);
}

static inline struct skcipher_alg *__crypto_skcipher_alg(
	struct crypto_alg *alg)
{
	return container_of(alg, struct skcipher_alg, base);
}

static inline struct crypto_istat_cipher *skcipher_get_stat(
	struct skcipher_alg *alg)
{
	return skcipher_get_stat_common(&alg->co);
}

static inline int crypto_skcipher_errstat(struct skcipher_alg *alg, int err)
{
	struct crypto_istat_cipher *istat = skcipher_get_stat(alg);

	if (!IS_ENABLED(CONFIG_CRYPTO_STATS))
		return err;

	if (err && err != -EINPROGRESS && err != -EBUSY)
		atomic64_inc(&istat->err_cnt);

	return err;
}

static int skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize)
{
	u8 *addr;

	addr = (u8 *)ALIGN((unsigned long)walk->buffer, walk->alignmask + 1);
	addr = skcipher_get_spot(addr, bsize);
	scatterwalk_copychunks(addr, &walk->out, bsize,
			       (walk->flags & SKCIPHER_WALK_PHYS) ? 2 : 1);
	return 0;
}

int skcipher_walk_done(struct skcipher_walk *walk, int err)
{
	unsigned int n = walk->nbytes;
	unsigned int nbytes = 0;

	if (!n)
		goto finish;

	if (likely(err >= 0)) {
		n -= err;
		nbytes = walk->total - n;
	}

	if (likely(!(walk->flags & (SKCIPHER_WALK_PHYS |
				    SKCIPHER_WALK_SLOW |
				    SKCIPHER_WALK_COPY |
				    SKCIPHER_WALK_DIFF)))) {
unmap_src:
		skcipher_unmap_src(walk);
	} else if (walk->flags & SKCIPHER_WALK_DIFF) {
		skcipher_unmap_dst(walk);
		goto